Vinyldibenzofuran polymers



Patented Feb. 21, 1950 "VINYLDIBENZOFURAN POLYMERS I Edward A. Kern and Royal K. Abbott, In, Pittsfield, Masa, assignors to General Electric Company, a corporation of New York No Drawing. Application December 11, 1944, Serial No. 567,786

9 Claims. I The present invention relates broadly to polymers of vinyl compounds and their preparation.

More specifically the invention is directed to the the preparation of vinyl compounds, and more specifically the preparation of vinyl-substituted dibenzofurans. is described and claimed. We have discovered that these monomeric materials may be polymerized and the present invention is specifically directed to the polymerization of the monomeric materials described and claimed in the aforesaid Abbott application.

We have found that "the polymerization of vinyl-substituted dibenzofurans, e. g., 2-vinyldibenzofuran; may be accomplished by polymerizing the monomer itself, a solution thereof or in the form of an emulsion or suspension. The readiness and speed of the polymerization depend greatly upon the purityof the monomer. The purer the monomer, the greater is the ease and rate of polymerization and the higher the molecular weight of the polymer. The physical properties of the polymers produced are to a large extent dependent upon the method of polymerization. Polymerizations carried out at high temperatures or at a very rapid rate usually produce a product that is discolored and of low molecular weight. In order to produce valuable polymerization products. careful control of the polymerization is necessary. 1 a

The polymerization may be accelerated by the use of catalysts, examples of which are BFz, SnCl4,

SbCls, organic or inorganic peroxides, air, the halogens, oxygen, ozone, the halogen acids, light or short wave length, and substances such as activated carbon or copper which possess large surface areas. Smallamounts of solvents have little eifect upon the rate of polymerization. Larger amounts tend'to favor the formation of short chain lengths and often produce a period of induction causing an interval to elapse between the addition of the catalyst and the beginning of polymerization.- The monomer may in general be inhibited by the same inhibiting agents that retard the polymerization of styrene.

The polymers possess ingeneral the physical properties of polystyrene except that the heatdistortion temperature is considerably higher. For example, the heat-distortion temperature of signed to the assignee of the present invention,

iii

. 2 poly-2-vinyldibenzofuraniis'atleast 40 0. higher than polystyrene. It may be cast, pressed, extruded, rolled, machined, injection or pressure molded. In general, it can be treated as any other thermoplastic material. The monomeric 2-vinyldibenzofuran is especially valuable as a solventless varnish or an impregnating medium. Because of its high boiling point, a. vacuum can be applied to it without undue-loss by vaporization. The impregnated or cast products can then be polymerized in place.

' Poly-2-vinyldibenzofuran is in general compatible'with the same materials as polystyrene. It can be plasticized in general by the same plasticizers. Its electrical properties are of the same order, making it very valuable for insulation.- It is a low loss thermoplastic resin. The polymerization products of 2-vinyldibenzoiuran can be employed for the manufacture of products which require a greater degree of heat resistance than styrene, polyethylene, methyl methacrylate, etc. It may. be extended in the plastic condition and then cooled. This orientation of the polymer imparts special mechanical properties to films, threads, tubes, ribbons and rods formed in this manner.

Since polyvinyldibenzofuran possesses low loss characteristics, a high dielectric constant, and a flow point in the neighborhood of 120 C., it is especially desirable for use in electrical and electronic equipment. 7

Where softening point and strength are of secondary importance, softening agents or plasticizers may be added. Such products ,may be used as synthetic leathers andshow the general characteristics of a plasticized vinyl resin.

The polymer may be ground and suitable fillers such as a-CelllllOSe, mica dust, oxides of titanium, talc, zinc oxide, magnesium oxide, asbestos, quartz, wood flour, cellulose, or wool fibers, etc, may be added to produce a desirable molding compound.

The following examples will further illustrate how the invention may be carried out in practice but the invention is not restricted by these examples: I

, ltmmple 1 9 g. of potassium hydroxide, 3 g. potassium carhonate and 3 g. of potassium persulfate are added to 200 g. of water. This solution is'mixed vigorouslywith 4.7 g. stearic acid dissolved in 100 g. of 2-vinyldibenzofuran. The resulting emulsion is heated at C. for 24 hours with constant shaking. After precipitating, the polymer is dissolvedinbensenesnd white,

reprecipitstedpowdery poly-fl-vinyldibensoiuran I obtained in good yield. Instead of potassium persuliate there may also be employed, as m in! penulfate, or an organic or inorganic peroxide, perborates, ozone, oxygen, air or other agents supplying oxygen. The amount oi the nqueom, layer and the natureoi the emulsiiying agent varied within wide limits.

Example 2 v 50 g. of 2-vinyldibensoiuran is dissolved in 50 g. of chlorobenzene. oi 1% oi lauroyl peroxide is added and the resulting solution is subjected to a temperature of 100 C. for 48 hours. vA very viscous solution is obtained iromwhich the poly mer is obtained by precipitation with methyl ing polymer is oi longer chain length and sesses improved physical properties.

Example 4 a 1 100 g. of 2+vinyldlbenzoiuran is'dissolved in 100 g. of chloroben'zene'. Ten drops oi the addition compound of BF: and diethyl'ether are dissolved in 50 g. of chlorobenzene and this solution added to the solution oi monomer in monochlorobenzene. The monomer begins to polymerize at once with the vigorous evolution of MUM:

4 Example 7 100 g. oi 2- vinyldibensoim-an is dissolved in 200 g. oi benzene and heatedunder reflux ice iour days. The polymer is obtained in the iorm oi a white powder by precipitation with methyl trample 8 100 g. of recrystallized Z-vinyldibe'nzoiuran is heated for 12 hours at 85 C., for 8 hours at 100' I C., and ior 6 hours at 125 C. A clear, hard mass is obtained. This material is well suited ior the preparation of films, coatings, and lacquers. Very pure recrystallized monomeric '2-vinyldibensoimuiizntiardens aiter heating at 65 C. ior 80 Example 9 readily undergoes chemical transformations: as,

heat. -The monomer islcompletely converted to a polymer oi relatively low molecular weight. 4 Example 5 100 g. of z-vinyldibenzoiuran which has been recrystallized from petroleum ether is heated at 65,? C. for 12 hours. -A ,hard, clear, glassy mass is obtained. If this massis dissolved inbensene and then precipitated in such a manner that20% of the lower molecular weight polymers are not precipitated, the resulting polymer is oi high molecular weight. This material yielik a polymer which has high impact and ilexural strength and a heat-distortion point above 120' C. The hard, glassy mass also provides an base for a molding powder.

' Example 6 3 100 g. of 2-vinyldibenzoiuran is dissolved in 150 g. of toluene and a little boron trifluoride is added in a current oi nitrogen. The polymerization is carried out at 10? C. with constant agitation. The beginning oi the polymerization is marked by an increase in This first reaction takes place with vigorous cooling so that the temperature does not rise more than 5 C. when this flrst reaction subsides, :a

little more boron trifluoride is introduced; 'This process is repeated until there is of further reaction. The whole polymerisation mass is. then allowed to stand at 10 C. for 16 hours after whichthe reaction is essentially complate. This mixture may-then be evaporated under vacuum to producea glassy mass or the polymer can be precipitated out of solution-with ior example, chlorination, nitration and sulphonation, and these products may be used as soiteners ior poly-z-vinyldibenzoiuran.

Ezample'm I 7 A mixture of 300 g. of il-flnyldibenzoiuran, g. of water, and 3 g. oi sodium peroxide is heated at C. for 24 hours in a pressuretight vessel. The resulting reaction product is 'ground, washedwith water, and then extracted with methanol to remove any unpolymerized 2-vinyldibenzoiuran. In this case the amoimt of the aqueous layer and the nature of the catslyst may be-varied within wide limits. Instead of a peroxide. omen, air, ozone, or an oxygensupplying compound may be used. When this polymer is dissolved in suitable-solvent it yields solutions which may be worked up into glass clear and colorless films. The physical properties oi these fllms may be improved by extending while in the plastic condition and then, allowing to cool.

Example 11 A solution of 100 parts oi z-vinyldibenzoiuran in 100 parts oi trichlorethylene is slowly run into tion product is precipitated in the form oi as white precipitate by the addition of methyl alcohol. The product thus obtained may be used in the manufacture of electrical equipment. 7

It will be evident from the foregoing examples of they preparation of poly-2-vinyldibenzoiuran thatpolymers may be prepared from the monomeric vinyl-substituted dibenzoiurans in a variety of ways, with or without catalysts, at normal, subnormal and elevated temperatures, at atmospheric pressure,reduced pressure and pressures above atmospheric, with or without solvent and II wither without soiteners or plasticizers."

Although the invention has been specifically illustrated by the use of 2-vinyldibenzofuran as the monomeric material from which polymers are prepared, other vinyl-substituted dibenzofurans may be used, such as, for example, 4-vinyldibenzofuran, the preparation of which is described in the copending application of Abbott above-referred to.

The polymers of the present invention, as noted particularly in the foregoing description and examples, have valuable physical and electrical characteristics, such as high softening point and low power factor of importance in connection with the use of the polymer as dielectric material in high frequency electrical apparatus. The polymers may be dissolved in various solvents and applied to paper, glass cloth and other backing material to form sheets which are useful as dielectrics in capacitors, or they may be used to form films.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Polymeric 2-vinyldibenzofuran.

2. Polymeric 4-vinyldibenzofuran.

3. The method of preparing a. polymeric monovinyldibenzoiuran which comprises heating a monovinyldibenzofuran.

4. The method of preparing polymeric 2-vinyldibenzofuran which comprises heating 2-vinvldibenzofuran.

5. The method of preparing a polymeric mono- 6 vin'yldibenzoturan which comprises heating a monovinyldibenzofuran in the presence of a po merization catalyst.

6. The method of preparing a new synthetic composition which comprises heating 2-yinyldibenzofuran under superatmospheric pressure in an aqueous medium containing a polymerization catalyst which supplies oxygen under the conditions of polymerization, and isolating the resulting polymeric 2-vinyldibenzofuran.

7. The method of preparing a new synthetic composition which comprises heating an emulsion containing 2-vinyldibenzoiuran and a polymerization catalyst which supplies oxygen under the conditions of polymerization, and isolating the resulting polymeric 2-vinyldibenzofuran.

8. A polymeric monovinyldibenzofuran.

9. The procws which comprises applying heat to monomeric 2-vinyldibenzofuran in the presence of a polymerization catalyst until a polymer is formed.

EDWARD A. KERN. ROYAL K. ABBOTI, Jn.

REFERENCES CITED FOREIGN PATENTS Country Date Great Britain June 22. 1988 Number 

8. A POLYMERIC MONOVINYLDIBENZOFURAN. 